Spatial tuning of the pattern ERG across temporal frequency |
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Authors: | T. Berninger R. P. Schuurmans |
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Affiliation: | (1) Arbeitsgemeinschaft II. Physiologische Abteilung des Max-Planck-Instituts fur Physiologische und Klinische Forschung, W.G. Kerckhoff-Institut, Bad Nauheim, W. Germany;(2) Augenklinik der Johann Wolfgang Goethe-Universitat, W. Germany;(3) Universität Augenklinik, Mathildenstr. 8, 2 München, W. Germany |
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Abstract: | The spatial response function of the electroretinogram (ERG) to contrast checkerboard pattern reversal at several check sizes was determined at a fixed contrast. The influence of the rate of modulation on the spatial response function was assessed: Reversing square wave patterns were presented at eight temporal frequencies ranging from 1 to 25 reversals per sec; The waveform consisted of an initial positive and a subsequent negative deflection. Irrespective of the temporal frequency, the spatial response function of the positive component did not show a spatial tuning. The amplitude of the negative component exhibited a pronounced attenuation of the response at check sizes larger than optimal. Mean maximal amplitude was found at an optimal check size between 25 and 50 min of arc. A distinction between a positive or negative component was not made for temporal frequencies higher than 10 reversals per sec, since the wave-form at these modulation rates consisted merely of a sinusoidal steady-state response. The spatial response function obtained at 14 reversals per sec; resembling that of the negative component, exhibited a prominent spatial tuning. The results demonstrate that the pattern ERG has at least two components: a positive component which is not specific to changes in retinal distribution of contrast, followed by a negative wave showing spatial tuning across temporal frequency. |
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Keywords: | electroretinogram (ERG) pattern reversal spatial tuning temporal frequency |
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